Wisconsin's first Passive House â€” a highly insulated type of construction that cuts energy costs by up to 90 percent - is currently being built just north of Hudson, WI. At left, workers finish installing solar panels May 27, 2010.(Pioneer Press: Chris Polydoroff)

A local physician is building a house in Wisconsin without a furnace — it won’t need one.

Rising over the St. Croix River Valley, the 1,940-square-foot, three-bedroom home will use solar power and the latest in energy-efficient construction. Designed to let in the maximum amount of sunlight, its walls are 11 inches of insulated concrete surrounded by 11 inches of exterior foam insulation.

In extreme cold, electric heaters in the floors can help warm the entire house.

“On the coldest, cloudiest days of the winter, we’ll need the equivalent of like 2,500 watts, which is basically a couple of handheld hair dryers,” said Dr. Gary Konkol, who is building the one-of-a-kind home in the town of Hudson, Wis.

Once completed, Konkol’s house will be carbon-neutral — that is, it will produce at least as much electricity as it consumes.

The home will also be a “passive house,” a highly insulated type of construction reducing heating and cooling needs 90 percent to 95 percent and overall energy consumption 70 percent to 80 percent, said Katrin Klingenberg, executive director of the Passive House Institute US.

While there are tens of thousands of such buildings in Europe, there are only about a dozen in the U.S. certified as passive homes, Klingenberg said. Konkol’s home will be the first in Wisconsin and the first of the kind in the country to also be carbon-neutral.

Konkol and his late wife, Christine Lassa, who died last year from cancer, were searching several years ago for a way to build an environmentally friendly home when he spotted an article about passive housing, which started in Germany in the 1990s.

“I read it and I said, ‘Wow. This looks like it is it,’ ” said Konkol, who practices family medicine in Woodbury.

He sought out architect Tim Eian, of Minneapolis-based TE Studio, who had training in passive house design. And plans for the Hudson home soon began.

“This whole model is really built on the paradigm that we’re on a finite planet with finite resources, and these resources need to be managed,” Eian said.

Konkol’s house will be connected to the power grid, but a solar array is expected to produce enough energy to make the home carbon-neutral for a household of two. Even most of the home’s hot water will be provided by a solar system on the roof.

Meanwhile, a German-made ventilation system will pump new air in and old air out of the home. A heat exchange — which uses 600 feet of underground, liquid-filled tubing — cools the air in the summer and warms it in the winter. Heat from escaping air is also captured and pumped back into the home during cooler months.

In addition to the thick walls, the home sits on a foot of insulation, and 14 inches of insulation are in the flat roof.

“If you take (insulation) to a certain level, you can essentially omit your traditional heating system all together,” Eian said.

While Konkol’s home is tightly sealed — fitted about five times tighter than traditional construction — air continues to be circulated throughout. Sensors detect fluctuations in room temperature and humidity and adjust airflow accordingly, Konkol said.

“If there are five or 10 people over, that’s going to change the dynamic of the air, and the ventilation system will compensate,” he said.

Even the weather is factored in. A computer on the roof reads various weather conditions. If sunlight is causing the home to overheat, the system will lower mechanical shades outside the windows.

Konkol declined to divulge how much the home is costing, saying he thought the amount might “discourage people from doing something like this.” But if he sells the home, Konkol said, he likely won’t get back what he paid for it.

The savings in energy costs, however, are expected to be significant, Eian said.

“You end up spending a little bit more up front, and then you have tremendous savings over time,” he said. “So you have to have time on your side.”

The house is expected to be finished in August.

Constructing a home to passive house standards — which include requirements for air tightness, heat and energy use — typically costs 10 percent to 18 percent more than traditional construction in the U.S., said Klingenberg, whose institute certifies such homes.

Klingenberg started the institute in 2007 after seeing the movement take off in Europe.

Her home, built in 2003 in Urbana, Ill., is the first passive home in the nation, although it is not certified, Klingenberg said. The first building certified to passive house standards is Concordia Language Villages’ Waldsee BioHaus in Bemidji, which was finished in 2006.

While new home construction has slowed across the country, Klingenberg has started to see an increase in passive house projects. Right now, about 30 are in the precertification stage, she said.

“We had a pretty good sense, just based on the developments in Europe and how quickly it’s grown over there, that it would sooner or later also repeat in the United States,” Klingenberg said.

“I think a year from now, we’ll have about 500 homes on the ground,” she added. “In 10 years, hopefully we’ll have many tens of thousands.”

Andy Rathbun can be reached at 651-228-2121.

How It Works

Summer: Liquid in a 600-foot underground loop is connected to a heat exchange, which cools and dehumidifies outside air being vented into the home. Exterior shades can block the sun from entering the home’s large windows.

Winter: Large, highly efficient windows use sunlight to heat the home, and the house’s thick, tight insulation keeps heat from escaping. The ventilation system warms outside air with the same heat exchange used in the summer and takes the heat out of exhaust air. Floor heaters kick in on extremely cold days.

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